So the Gamepad last aprox 3 hrs and for some of us this isnt enough.

Enter Nyko to save us from being plugged in consantly.

Power Pak for Wii U: $24.99

Triple the capacity and play time of the original GamePad
Includes mini screwdriver for easy installation
Works with the existing Nyko and first party charging solutions
Fits entirely into the existing GamePad Battery compartment - no additional bulk
CE and EL certified high quality lithium polymer battery
Release Date 3/22/2013

Wii U UBoost: $24.99

Play up to 2x longer
Easily clips on to GamePad, no installation required
Works in conjunction with the GamePad battery
Built-in stand for watching steaming content
Lightweight design
Charges through the stock Nintendo GamePad adaptor
Release Date NOW

When is it released?

I included the release dates.

Uboost is available now and power pak is 3/22/2013. Check Gamestop.

Hope it launches n the UK soon too.

I do not see the point in this to be honest...

more than doubling the GamePad battery life, I definitely see the point in this. I hope Nintendo release something along these lines, although it's annoying they went with the small, lowish capacity battery in the first place, weight and/or price considerations be damned

What's the point of this when a charger will always be near you when you're playing?

You'll be able to still use it wirelessly while being able to move it around.
Granted, I still don't think its worth it - but for some I suppose it makes sense.

$24.99 seems a bit much just for that though.

so you can be completely wireless for extended sessions? plenty of people definitely care enough to buy a bigger battery.

Just doesn't seem worth the money. Of course, that's my opinion.

How can $25 be too expensive?
The Galaxy Nexus extended battery is 2100 mAh and is $31 currently. This Power Pak is $25 and is 4000 mAh.

Being tether to a plug sucks.
I understand you personally might not see value in it but it is great value

You can buy an extra GamePad AC adapter from Nintendo for $19.99, but that would be plugged in while playing. As somebody else mentioned, this would give you the "wireless" freedom to still move around easier.

I have to move to a different, less comfortable, seat for the cable to stretch and unplug the cable from the charging stand, which normally runs behind my desk, making plugging it back in particularly onerous. None of that is exactly the worst that happens in the world but if I can avoid it then so much the better.

Finally! This will be so useful for me seeing as I played my Wii U for 12 hours and 26 minutes straight yesterday (I played so much because it was my first weekend with it, lol)...I had to charge the gamepad multiple times and I couldn't sit on my couch while charging it because of the position of my electrical outlets. So if Nyko can really provide 9-10 hours on one charge I say it's a small price to pay for my comfort!

Or power usage?

This is not a handheld. It will always be near outlets and it can stay charged for up to 3 hours. If you game for longer than that, that's your problem. Aside from that, it's pointless.

Meh. I wouldn't trust Nyko with a battery. They make accessories all the time, but one mishap that destroys anything and Nintendo will void your warranty completely with unlicensed gear. I'd rather buy a Nintendo brand one that doesn't void the warranty if something bad happens, or if they license it.
Chances are that you're gonna be close to an outlet anyway. I'd rather buy an extension cord honestly, but my outlet isn't that far anyway, and I rarely run out unless I walk away and leave the console on without the gamepad being on the charge stand.

It does indeed have a point. Near an outlet doesn't really work, because for many games you need to be able to move the gamepad around a lot. And saying it lasting 3 hours is long enough for someone to play for the day doesn't really work. So I play 3 hours, and the gamepad needs to be charged, but someone else wants to play WiiU? The bigger battery does have a reason to exist. It doesn't apply to everyone, which could be one of the reasons why Nintendo felt the cheaper and lighter 3 hour battery would suffice for the system.

@scar would using this really void your warranty?

Yup. Well, if any official Nintendo product doesn't work correctly, or is damaged by use of unlicensed products, it's in Nintendo's policy to void the warranty, because it is no fault of theirs. They don't recommend using 3rd party anything. They try to avoid, 'Why won't my Nyko Wand+ work?' questions at any cost. These products work, but aren't usually tested as heavily as how Nintendo tests them in their own facility. If they find any trace that your Nintendo product was messed with, like opening the casing, or had 3rd party products used on it, the warranty is no more.